Bar Code Technology
Abstract Bar code technology pervades our lives.From product labels to personal identification cards to asset tracking tags, bar codes add speed and accuracy to the flow of many kinds of information.This technology was invented as a solution to the problem of high labor costs and inaccurate inventory methods in retail grocery stores. Joseph Woodland of Drexel University invented a solution that was eventually made economically feasible by the availability of low-cost lasers, a universally-accepted bar code standard, and digital data storage and transfer systems.Bar codes have increased the speed and accuracy of all parts of the supply chain from raw stock materials to finished goods to retail sale, and has given us the ability to track items at any point in the process from origin to destination.This, and its related technologies have driven down costs, increased efficiencies, improved supply movement and inventories, and helped make products and information more accessible to people in all parts of the world.
Bar Code Technology
Introduction
In the 1940’s, when people wanted to make a retail purchase, their items were taken from the store shelves and brought to the checkout clerk for tallying on a cash register.The cost of the purchases were totaled on the machine, where the information was stored on a roll of paper.The product removed from the shelves would later be noted by recording the new quantities on a sheet of paper.The store owner or manager would not know when to order new inventory or in what quantity until a tedious process of scouring the inventory sheets was done.These kinds of lengthy human labor tasks existed all the way through the supply chain.Not only is human labor inefficient, it is inaccurate.Both of these characteristics are wasters of capital.The desire and competitive need to reduce these problems drove a business leader to look for a solution.This is what motivated the invention of the bar code and the bar code reader.But it did more than that.It initiated an entire information technology industry that reshaped the way that people work, shop, and get information.
The invention of bar codes
As businesses always do, grocery stores were looking for ways to improve the efficiency and accuracy of managing their inventories and operations.In other words, they were trying to lower their costs and get better control of activities in their stores.Tracking of materials along the entire supply chain – from harvesting or extracting raw materials, to processing, shipping, and going into and out of stores – was done entirely by keeping written records by hand.This involved the counting and recording of various data by people.What product, how many, from where, to where, at what cost, on what date, at what time, and on and on.At each step of the long process, a human was counting things, and making calculations, and writing them down.Humans are prone to error.And by the 1940’s it was well understood that they were also slower and more expensive to employ.Additionally, there is also the problem of shrinkage – the reduction of inventory from spoilage, damage, and most notably, theft.One of the weaknesses of using stickers to indicate the price of an item is that they can be removed and replaced.Often, a devious shopper would remove the price sticker from a more expensive item and replace it with a sticker from a less expensive item.As long as the price difference wasn’t extreme, the checker wouldn’t notice, and charge the customer the lower price.So the search began for a automated way to perform these tasks.
A local grocery chain executive, and donor to the Drexel Institute of Technology, asked a dean to work on a means of automating the inventory process.This lead to a couple of Drexel graduate students taking an interest in the idea, and they began working on a solution.Joseph Woodland and Bernard Silver began by studying the film sound scanning technique of Lee DeForest in 1926.It consisted of varying amounts of light transmission along the edge of the film to produce a time-varying signal detected by a photomultiplier.Thus, the optical signal was converted to an electrical signal and amplified into sound.Woodland combined this varying light level idea with the dots and dashes of Morse code.The dots and dashes of the Morse code were extended vertically to form wide and narrow bars with spaces between.Then, moving the bars and spaces across the path of light between the bulb and the photomultiplier would produce a transmitted signal that could be decoded electronically, making the job of reading and entering product information quick and error-free (and greatly reducing the amount of human labor involved).
As it turned out, there were some technological hurdles to overcome.The light source was a scorching 500 watts, enough to burn the bar codes it was reading, and the device was about the size of a desk.Woodward invested his personal assets heavily in the endeavor to invent a device with great utility and appeal, but was not able to overcome these and other technical hurdles at that time.
How bar code technology was made possible
About ten years later, an outdoor application was invented by David Collins at Sylvania to read bar codes on trains.This improved apparatus used reflected light, rather than transmitted light to detect the bar code.This dramatically reduced the amount of optical power needed to read the codes, and was a key factor in the evolution of bar code reading hardware.In the mid-1960’s, the helium-neon gas laser became available.This was the low-cost, low energy output light source that was needed to make bar code reading a commercially viable solution.Subsequently, Collins left Sylvania to form Computer Identics, and made use of the He-Ne laser in a reader for General Motors to read bar codes on axles at the Pontiac, Michigan plant.With the low-cost laser and the use of reflected light, it was then a matter of finding the right bar code, and a means of handling the data.
This is where Woodland came back into the picture, this time in a supporting role.He was assigned by IBM to work on a universally applicable bar code design.A colleague, George Laurer, came up with the key features that made what became known as the universal product code or UPC.(Marling, 179)His design was selected over many others that were submitted by other companies in response to a request from the Uniform Grocery Product Code Council (UGPCC), which was formed to find a standard bar code for grocery use.As the name implies, the power and utility of the Universal Product Code is that it can be used by all stores to identify all products from all manufacturers.By adding a 13th digit to the code to identify country of origin, Laurer made it truly universal.This code, known as European Article Number (EAN)is identical in appearance to the UPC, but has a modified decoding algorithm and includes an additional human-readable digit below the code.
Along with the new bar code standard, new standards had to be made for printing bar codes and verifying their quality, and for product labeling.The UGPCC became simply the Uniform Code Council (UCC), and was given responsibility for these standards.There are several other bar codes in popular use, most notably Code 3 of 9 which is used primarily by the Department of Defense and the automobile industry, and Interleaved 2 of 5 which is used for shipping containers and case packaging.
These standards gained acceptance only by industry leaders pushing for adoption so that economic gains could be realized.Kroger and Albert Hein were among those who promoted bar coding.There was the dual obstacle of getting suppliers to print bar codes on their labels and getting grocers to install reading equipment.Only if there was general acceptance would the equipment become economical for any company to implement.So adoption was slow.Once an economical method of printing and reading bar codes was established, the problem of how to handle all of the data became the last hurdle to overcome.
Computer technology was in its infancy in the 1970s and only began to achieve large scale use in the 1980s, partly helped along by the personal computer revolution.Although the mainframes used to process and store the inventory data captured by bar code readers were quite different from personal computers, the entire computing industry was transformed by the PC, and this helped the adoption of bar code technology.Today, nearly every supermarket cash register is a specialized personal computer.In fact, many run the Microsoft Windows operation system and run applications just as any PC. The back office servers are also similar to PCs.
How the industry grew
One of the early uses for bar code readers was as verifiers for the printing of bar codes to ensure that they were printed with sufficient quality to be reliably read by the bar code readers.Metrologic Instruments, of Bellmawr, New Jersey, was one of the makers of printing verifiers.Metrologic was founded by C. Harry Knowles, who had gotten started in his own business when he advertised a build-your-own laser kit in Popular Mechanics in 1968.
Several other bar code scanning manufacturers sprang up, including Spectra-Physics, ICL, Datachecker, Photographic Sciences Corporation, and Symbol Technologies.Eventually, the gas laser was supplanted by the solid state laser as the common choice for low-cost laser bar code readers.In parallel, the light pen – manufactured by Welch-Allen and others - was commonly used as an ultra low cost reader for low throughput applications.It consisted of a pen-sized wand with a cable attached to one end and an optical transceiver at the other end.To read a bar code, one simply swiped the wand across the code, as if drawing a line through it.
During this the 1980s, as bar code technology became more popular, the method of processing the optical and electrical signals inside the bar code readers improved.Since the information is stored in the widths of the bars and spaces in the code, the only important characteristic of the signal is the part that corresponds to the edges of those elements.The process of finding these places in the signal is called edge detection.Initially, this was done simply by comparing the analog signal with a threshold.For example, any part of the signal above the threshold was considered a bar and anything below was a space.In 1986, Donald Cherry of Spectra-Physics invented the second derivative zero-crossing method of edge detection.As the name implies, this involved taking a first derivative of the signal, then an second derivative.The zero crossings of the second derivative of a function correspond to times when the function has the greatest rate of change.This occurs when the spot of focused light crosses the edge of the bar.Soon, nearly all manufacturers were using some variation of this method, which improved the robustness of bar code readers and enabled first pass read rates approaching one hundred percent.
More recently, integrated circuit cameras, similar to the ones used in cell phones, have been invading territory once dominated by the laser scanners.These devices literally take an image of the bar code, and software algorithms are used to find the bar code in the image and decode it.On the horizon are radio frequency identification (RFID) tags, such as the ones used at vehicle toll-collection sites, which promise to replace bar codes as the most common means of automatically identifying everything from food, clothing, vehicles, and corporate assets to animals and humans.All of this tagging and tracking accelerates the availability and utility of the associated information, but raises privacy concerns as well.These issues will be discussed later.
The effect of bar coding on how we do business
Bar coding has now pervaded all manner of commercial enterprise.At every point in the supply chain, bar codes help identify what was there and when.The thirst for information has driven its use into every aspect of operations.With a PC on every manager’s desk, accurate up-to-the-minute information on the whereabouts of packages, equipment, parts, vehicles, documents, and even people is at their fingertips.A side benefit is that consumers can also get fresh information, such as the location of the book they just ordered from Amazon.com.They just click on the UPS tracking link, and through an internet connection they can find the time, date, and location that the package was last handled – and most important when delivery is expected.Certainly, they had some idea of when the book would be delivered when they ordered it, but that was with an uncertainty of days.Now they can get an estimate with an uncertainty of hours.With that kind of accuracy, they can do a much more effective job of planning their day.This is the same kind of advantage that tracking information gives businesses.
One of the early uses of bar code technology was in libraries, to track loans of books and other materials.This application has expanded into private libraries such as those in law firms.Once such firm uses portable readers to check inventory lying on busy lawyers desks.If one person checks out a book, and then another borrows it from the first person, this system discovers who the new borrower is and logs that information so that anyone looking for a particular item will be able to locate it without following a trail of evidence gleaned from personal interviews.
The effect of bar coding on quality of life
Another side benefit of bar code technology is its role in improving the efficiency of our daily lives.Checkout lines are shorter than ever before, meaning we can make larger amounts of purchases at once and reduce the amount of time spent at the checkout.Store owners in Lebanon have been able to increase inventory because they spend less time on that task.This gives customers more choices.
As previously stated, we can track shipments.Gaining access to secure rooms and buildings (such as college computer labs and libraries) can be done at any hour of the day, any day of the year.The owners of such facilities are more confident in allowing this access because they are secure in the knowledge that they know who was in the building at particular times.The other side of the coin is the giving up of our privacy in these situations.Just as bar codes and RF tags make the tracking of shipments easy and accurate, they do the same thing for tracking the activities of people.Under the premise of better safety and security in a hurricane Katrina type disaster or other emergency, Motorola has offered a solution involving the use of bar-coded or RFID tagged wrist bands.This is purported to help provide necessary services such as housing and medical care to those in need.However, such capabilities can often lead to other uses that may not be so altruistic.Certainly, Motorola’s motivation is to sell more of its products, which include many bar code and RF tag readers and other mobility devices.(Motorola purchased Symbol Technologies in 2007).Although RFID technology is threatening to replace bar codes, the cost of placing an RF tag on every consumer product is still to high – up to 30 cents per tag, compared with half a penny per label for bar codes.There is also a technical challenge: RF tags cannot be read through liquids such as water, soda, and laundry detergent.Therefore, the lure of identifying an entire basket of goods at the grocery checkout is still in the future.For now, bar codes will continue to be an ever-important, ever less conspicuous part of our everyday lives. References
Palmer, Roger C.The Bar Code Book: Reading, Printing, and Specification of Bar Code Symbols.Peterborough, NH: Helmers Publishing, 1995.
United States Patent 2,612,994.Classifying Apparatus and Method.Norman J. Woodland and Bernard Silver. 1952
United States Patent 6,073,849.“Electronic edge detection system using a second derivative signal processor”.Donald Cherry,1986.
Marling, William H.How “American” is Globalization?Baltimore: The Johns Hopkins University Press, 2006.
Moser, Mary Anne, and Douglas MacLeod, editors.Immersed in Technology, Art and Virtual Environments.Cambridge, MA: The MIT Press, 1996.
Campbell-Kelly, Martin, and William Aspray.Computer: A History of the Information Machine.Boulder, CO: Westview Press, 2004.
Collins, David Jarrett, and Nancy Nasuti Whipple.Using Bar Code: Why it’s Taking Over.Duxbury, MA: Data Capture Institute, 1990.
Cuddy, Colleen.Using PDAs in Libraries: A How-To-Do-It Manual.New York: Neal-Schuman Publishers, 2005.
Carroll, T.L.“Perceptions of pediatric nurses toward bar-code point-of-care medication administration.”
Koenig, Susan, and Ronald Koenig.“The magic wand [microform] : bar code technology in the California courts”.San Francisco, CA: National Center for State Courts, Western Regional Office, 1989.
Materials management and distribution [electronic resource]. Toronto, Maclean-Hunter.
Abstract
Bar code technology pervades our lives. From product labels to personal identification cards to asset tracking tags, bar codes add speed and accuracy to the flow of many kinds of information. This technology was invented as a solution to the problem of high labor costs and inaccurate inventory methods in retail grocery stores. Joseph Woodland of Drexel University invented a solution that was eventually made economically feasible by the availability of low-cost lasers, a universally-accepted bar code standard, and digital data storage and transfer systems. Bar codes have increased the speed and accuracy of all parts of the supply chain from raw stock materials to finished goods to retail sale, and has given us the ability to track items at any point in the process from origin to destination. This, and its related technologies have driven down costs, increased efficiencies, improved supply movement and inventories, and helped make products and information more accessible to people in all parts of the world.
Bar Code Technology
Introduction
In the 1940’s, when people wanted to make a retail purchase, their items were taken from the store shelves and brought to the checkout clerk for tallying on a cash register. The cost of the purchases were totaled on the machine, where the information was stored on a roll of paper. The product removed from the shelves would later be noted by recording the new quantities on a sheet of paper. The store owner or manager would not know when to order new inventory or in what quantity until a tedious process of scouring the inventory sheets was done. These kinds of lengthy human labor tasks existed all the way through the supply chain. Not only is human labor inefficient, it is inaccurate. Both of these characteristics are wasters of capital. The desire and competitive need to reduce these problems drove a business leader to look for a solution. This is what motivated the invention of the bar code and the bar code reader. But it did more than that. It initiated an entire information technology industry that reshaped the way that people work, shop, and get information.
The invention of bar codes
As businesses always do, grocery stores were looking for ways to improve the efficiency and accuracy of managing their inventories and operations. In other words, they were trying to lower their costs and get better control of activities in their stores. Tracking of materials along the entire supply chain – from harvesting or extracting raw materials, to processing, shipping, and going into and out of stores – was done entirely by keeping written records by hand. This involved the counting and recording of various data by people. What product, how many, from where, to where, at what cost, on what date, at what time, and on and on. At each step of the long process, a human was counting things, and making calculations, and writing them down. Humans are prone to error. And by the 1940’s it was well understood that they were also slower and more expensive to employ. Additionally, there is also the problem of shrinkage – the reduction of inventory from spoilage, damage, and most notably, theft. One of the weaknesses of using stickers to indicate the price of an item is that they can be removed and replaced. Often, a devious shopper would remove the price sticker from a more expensive item and replace it with a sticker from a less expensive item. As long as the price difference wasn’t extreme, the checker wouldn’t notice, and charge the customer the lower price. So the search began for a automated way to perform these tasks.A local grocery chain executive, and donor to the Drexel Institute of Technology, asked a dean to work on a means of automating the inventory process. This lead to a couple of Drexel graduate students taking an interest in the idea, and they began working on a solution. Joseph Woodland and Bernard Silver began by studying the film sound scanning technique of Lee DeForest in 1926. It consisted of varying amounts of light transmission along the edge of the film to produce a time-varying signal detected by a photomultiplier. Thus, the optical signal was converted to an electrical signal and amplified into sound. Woodland combined this varying light level idea with the dots and dashes of Morse code. The dots and dashes of the Morse code were extended vertically to form wide and narrow bars with spaces between. Then, moving the bars and spaces across the path of light between the bulb and the photomultiplier would produce a transmitted signal that could be decoded electronically, making the job of reading and entering product information quick and error-free (and greatly reducing the amount of human labor involved).
As it turned out, there were some technological hurdles to overcome. The light source was a scorching 500 watts, enough to burn the bar codes it was reading, and the device was about the size of a desk. Woodward invested his personal assets heavily in the endeavor to invent a device with great utility and appeal, but was not able to overcome these and other technical hurdles at that time.
How bar code technology was made possible
About ten years later, an outdoor application was invented by David Collins at Sylvania to read bar codes on trains. This improved apparatus used reflected light, rather than transmitted light to detect the bar code. This dramatically reduced the amount of optical power needed to read the codes, and was a key factor in the evolution of bar code reading hardware. In the mid-1960’s, the helium-neon gas laser became available. This was the low-cost, low energy output light source that was needed to make bar code reading a commercially viable solution. Subsequently, Collins left Sylvania to form Computer Identics, and made use of the He-Ne laser in a reader for General Motors to read bar codes on axles at the Pontiac, Michigan plant. With the low-cost laser and the use of reflected light, it was then a matter of finding the right bar code, and a means of handling the data.This is where Woodland came back into the picture, this time in a supporting role. He was assigned by IBM to work on a universally applicable bar code design. A colleague, George Laurer, came up with the key features that made what became known as the universal product code or UPC. (Marling, 179) His design was selected over many others that were submitted by other companies in response to a request from the Uniform Grocery Product Code Council (UGPCC), which was formed to find a standard bar code for grocery use. As the name implies, the power and utility of the Universal Product Code is that it can be used by all stores to identify all products from all manufacturers. By adding a 13th digit to the code to identify country of origin, Laurer made it truly universal. This code, known as European Article Number (EAN) is identical in appearance to the UPC, but has a modified decoding algorithm and includes an additional human-readable digit below the code.
Along with the new bar code standard, new standards had to be made for printing bar codes and verifying their quality, and for product labeling. The UGPCC became simply the Uniform Code Council (UCC), and was given responsibility for these standards. There are several other bar codes in popular use, most notably Code 3 of 9 which is used primarily by the Department of Defense and the automobile industry, and Interleaved 2 of 5 which is used for shipping containers and case packaging.
These standards gained acceptance only by industry leaders pushing for adoption so that economic gains could be realized. Kroger and Albert Hein were among those who promoted bar coding. There was the dual obstacle of getting suppliers to print bar codes on their labels and getting grocers to install reading equipment. Only if there was general acceptance would the equipment become economical for any company to implement. So adoption was slow. Once an economical method of printing and reading bar codes was established, the problem of how to handle all of the data became the last hurdle to overcome.
Computer technology was in its infancy in the 1970s and only began to achieve large scale use in the 1980s, partly helped along by the personal computer revolution. Although the mainframes used to process and store the inventory data captured by bar code readers were quite different from personal computers, the entire computing industry was transformed by the PC, and this helped the adoption of bar code technology. Today, nearly every supermarket cash register is a specialized personal computer. In fact, many run the Microsoft Windows operation system and run applications just as any PC. The back office servers are also similar to PCs.
How the industry grew
One of the early uses for bar code readers was as verifiers for the printing of bar codes to ensure that they were printed with sufficient quality to be reliably read by the bar code readers. Metrologic Instruments, of Bellmawr, New Jersey, was one of the makers of printing verifiers. Metrologic was founded by C. Harry Knowles, who had gotten started in his own business when he advertised a build-your-own laser kit in Popular Mechanics in 1968.Several other bar code scanning manufacturers sprang up, including Spectra-Physics, ICL, Datachecker, Photographic Sciences Corporation, and Symbol Technologies. Eventually, the gas laser was supplanted by the solid state laser as the common choice for low-cost laser bar code readers. In parallel, the light pen – manufactured by Welch-Allen and others - was commonly used as an ultra low cost reader for low throughput applications. It consisted of a pen-sized wand with a cable attached to one end and an optical transceiver at the other end. To read a bar code, one simply swiped the wand across the code, as if drawing a line through it.
During this the 1980s, as bar code technology became more popular, the method of processing the optical and electrical signals inside the bar code readers improved. Since the information is stored in the widths of the bars and spaces in the code, the only important characteristic of the signal is the part that corresponds to the edges of those elements. The process of finding these places in the signal is called edge detection. Initially, this was done simply by comparing the analog signal with a threshold. For example, any part of the signal above the threshold was considered a bar and anything below was a space. In 1986, Donald Cherry of Spectra-Physics invented the second derivative zero-crossing method of edge detection. As the name implies, this involved taking a first derivative of the signal, then an second derivative. The zero crossings of the second derivative of a function correspond to times when the function has the greatest rate of change. This occurs when the spot of focused light crosses the edge of the bar. Soon, nearly all manufacturers were using some variation of this method, which improved the robustness of bar code readers and enabled first pass read rates approaching one hundred percent.
More recently, integrated circuit cameras, similar to the ones used in cell phones, have been invading territory once dominated by the laser scanners. These devices literally take an image of the bar code, and software algorithms are used to find the bar code in the image and decode it. On the horizon are radio frequency identification (RFID) tags, such as the ones used at vehicle toll-collection sites, which promise to replace bar codes as the most common means of automatically identifying everything from food, clothing, vehicles, and corporate assets to animals and humans. All of this tagging and tracking accelerates the availability and utility of the associated information, but raises privacy concerns as well. These issues will be discussed later.
The effect of bar coding on how we do business
Bar coding has now pervaded all manner of commercial enterprise. At every point in the supply chain, bar codes help identify what was there and when. The thirst for information has driven its use into every aspect of operations. With a PC on every manager’s desk, accurate up-to-the-minute information on the whereabouts of packages, equipment, parts, vehicles, documents, and even people is at their fingertips. A side benefit is that consumers can also get fresh information, such as the location of the book they just ordered from Amazon.com. They just click on the UPS tracking link, and through an internet connection they can find the time, date, and location that the package was last handled – and most important when delivery is expected. Certainly, they had some idea of when the book would be delivered when they ordered it, but that was with an uncertainty of days. Now they can get an estimate with an uncertainty of hours. With that kind of accuracy, they can do a much more effective job of planning their day. This is the same kind of advantage that tracking information gives businesses.One of the early uses of bar code technology was in libraries, to track loans of books and other materials. This application has expanded into private libraries such as those in law firms. Once such firm uses portable readers to check inventory lying on busy lawyers desks. If one person checks out a book, and then another borrows it from the first person, this system discovers who the new borrower is and logs that information so that anyone looking for a particular item will be able to locate it without following a trail of evidence gleaned from personal interviews.
The effect of bar coding on quality of life
Another side benefit of bar code technology is its role in improving the efficiency of our daily lives. Checkout lines are shorter than ever before, meaning we can make larger amounts of purchases at once and reduce the amount of time spent at the checkout. Store owners in Lebanon have been able to increase inventory because they spend less time on that task. This gives customers more choices.
As previously stated, we can track shipments. Gaining access to secure rooms and buildings (such as college computer labs and libraries) can be done at any hour of the day, any day of the year. The owners of such facilities are more confident in allowing this access because they are secure in the knowledge that they know who was in the building at particular times. The other side of the coin is the giving up of our privacy in these situations. Just as bar codes and RF tags make the tracking of shipments easy and accurate, they do the same thing for tracking the activities of people. Under the premise of better safety and security in a hurricane Katrina type disaster or other emergency, Motorola has offered a solution involving the use of bar-coded or RFID tagged wrist bands. This is purported to help provide necessary services such as housing and medical care to those in need. However, such capabilities can often lead to other uses that may not be so altruistic. Certainly, Motorola’s motivation is to sell more of its products, which include many bar code and RF tag readers and other mobility devices. (Motorola purchased Symbol Technologies in 2007). Although RFID technology is threatening to replace bar codes, the cost of placing an RF tag on every consumer product is still to high – up to 30 cents per tag, compared with half a penny per label for bar codes. There is also a technical challenge: RF tags cannot be read through liquids such as water, soda, and laundry detergent. Therefore, the lure of identifying an entire basket of goods at the grocery checkout is still in the future. For now, bar codes will continue to be an ever-important, ever less conspicuous part of our everyday lives.
References
Palmer, Roger C. The Bar Code Book: Reading, Printing, and Specification of Bar Code Symbols. Peterborough, NH: Helmers Publishing, 1995.
United States Patent 2,612,994. Classifying Apparatus and Method. Norman J. Woodland and Bernard Silver. 1952
United States Patent 6,073,849. “Electronic edge detection system using a second derivative signal processor”. Donald Cherry, 1986.
Laurer, George. “Development of the U.P.C. Symbol”. http://bellsouthpwp.net/l/a/laurergj/UPC/upc_work.html 2001.
GS1 US. http://www.gs1us.org 2009.
Marling, William H. How “American” is Globalization? Baltimore: The Johns Hopkins University Press, 2006.
Moser, Mary Anne, and Douglas MacLeod, editors. Immersed in Technology, Art and Virtual Environments. Cambridge, MA: The MIT Press, 1996.
Campbell-Kelly, Martin, and William Aspray. Computer: A History of the Information Machine. Boulder, CO: Westview Press, 2004.
Collins, David Jarrett, and Nancy Nasuti Whipple. Using Bar Code: Why it’s Taking Over. Duxbury, MA: Data Capture Institute, 1990.
Cuddy, Colleen. Using PDAs in Libraries: A How-To-Do-It Manual. New York: Neal-Schuman Publishers, 2005.
Carroll, T.L. “Perceptions of pediatric nurses toward bar-code point-of-care medication administration.”
Koenig, Susan, and Ronald Koenig. “The magic wand [microform] : bar code technology in the California courts”. San Francisco, CA: National Center for State Courts, Western Regional Office, 1989.
Materials management and distribution [electronic resource]. Toronto, Maclean-Hunter.
Adams, Russell. “A Short History Of Bar Code”. http://www.adams1.com/history.html 2009.
Association for Automatic Identification and Mobility. (RFID web page). http://www.aimglobal.org/technologies/RFID/ 2009.
Motorola, Inc. “Evacuation Management: Tracking People and Assets” Solution Brief.
http://www.motorola.com/staticfiles/Business/Solutions/Industry%20Solutions/Government/Public%20Service/_Documents/Static%20Files/RO-99-2162.pdf 2009.